Mormon foreshadows the result of this war and lets us know that the Nephites will eventually prevail. Mormon’s purpose is not to write a novel where one builds suspense, but to use history to teach a moral lesson, that of the value in obeying the commands of God. Mormon is setting up the situation where there are many Nephites who do not obey God, and therefore this will be a more difficult war, even though it will eventually be won.